1. Field of the Invention
The present invention relates generally to fluid dispensing devices. More particularly, the invention concerns a novel dispenser for dispensing propofol, as well as analogous sedation agents, to patients with increased safety and efficiency, while reducing the probability of hospital acquired infections.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
A number of different types of medicament dispensers for dispensing various types of medicaments to patients have been suggested in the past. The traditional prior art infusion methods make use of a flexible infusion bag suspended above the patient. Such gravametric methods are cumbersome, imprecise, require many time consuming steps by clinicians, are susceptible to medication errors and require bed confinement of the patient. Periodic monitoring of the apparatus by the nurse or doctor is required to detect malfunctions of the infusion apparatus. Accordingly, the prior art devices are not well suited for use in those instances where the patient must be transported from one part of the healthcare facility to another.
Many of the state-of-the-art medicament delivery devices involve the use of electronic pumps to dispense the medicament from the dispenser reservoir. In the past, these types of devices have been the devices of choice for dispensing propofol (and other injectable sedation agents) and this equipment requires significant effort to prepare and administer the drug.
Propofol is a highly protein bound in vivo and is metabolized by conjugation in the liver. Its rate of clearance exceeds hepatic blood flow, suggesting an extrahepatic site of elimination as well. Its mechanism of action is uncertain, but it is postulated that its primary effect may be potentiation of the GABA—a receptor, possibly by slowing the closing channel time. Recent research has also suggested the endocannabinoid system may contribute significantly to propofol's anesthetic action and to its unique properties.
In recent years propofol has been widely used as an anesthetic agent for the induction of general anesthesia in adult patients and pediatric patients older than 3 years of age, for use in the maintenance of general anesthesia in adult patients and pediatric patients older than 2 months of age, for use in sedation for intubated, mechanically ventilated adults, and in procedures such as colonoscopy.
At the present time, propofol is commonly delivered through an electronic pump that is preset with the patient's weight (in kg) and a dosage increment measured in micrograms/kg/min. One prior art electronic pump that is presently in use is a pump sold by Baxter International, Inc, of Deerfield, Ill. under the name and style “.InfusO.R.”. This pump contains four separate dials. The first dial is to set the patient weight; the second dial is to set the dosage; the third dial is to set a bolus volume to initiate sedation; and the fourth dial is used to purge the syringe if there is any remaining propofol after the procedure. The Baxter pump has a magnetic plate that contains all the increments of the dials and the plates can be changed for different medications. By having removable plates, there is an increased possibility of medication error if the magnetic plate is not checked for increments for the correct medication or the correct concentration. The Baxter pump is typically used in the surgicenter setting where the anesthesiologist gives the patient an initial bolus of propofol for inducing sedation and the preset dosage is given in addition to gas anesthesia to keep the patient asleep during the operation.
Another pump that is presently in use is a pump sold by the Cardinal Health Company of Dublin, Ohio under the name and style “ALARIS PL”. The ALARIS PL syringe pump or ALARIS IVAC pump is used in conjunction with a Diprifusor syringe that is pre-filled with propofol. The Diprifusor is a target controlled infusion (TCI) system that was developed to enhance the control of IV anesthesia. With a TCI pump, a microprocessor manages the infusion rate and controls the syringe. The anesthesiologist enters the body weight of the patient, the age of the patient, and the dosage in microgram/ml. The Alaris pumps rely on the anesthesiologist entering the correct data minimizing the possibility of medication error but the dosage form is not the commonly used increment, (microgram/ml instead of microgram/kg/min) which relies on the anesthesiologist to convert the dosage and potentially increases the risk of medication error through miscalculation. The Diprifusor and TCI pumps are typically used in Europe where the pump is used to control sedation and anesthesia, but are thus far not dominant in the American surgical market.
Many current disposable infusion pump modalities also require the disposable pump to be filled by an attending clinician. These filling and preparation protocols present a number of serious challenges that can lead to serious medication errors, patient injury, or patient death. For example, a medication error can result from the clinician accidentally putting the wrong medicine into the delivery system. Additionally, filling an infusion pump in a non-aseptic environment (e.g. the operating room) can also pose challenges in maintaining drug and device sterility.
As will be discussed in greater detail hereinafter, the propofol dispenser of the present invention allows the anesthesiologist to create a basic “recipe” for propofol based sedation that could prevent patient complications. The dispenser of the present invention is particularly well-suited for use in the administration of propofol by non-anesthesiologists in low risk procedures, such as colonoscopies.
Another pharmaceutical agent appropriate for use in this novel dispenser technology is dexmedetomidine hydrochloride (Precedex), and related compounds. Precedex is indicated for sedation of initially intubated and mechanically ventilated patients during treatment in an intensive care setting. Precedex is typically administered by continuous infusion using a syringe of the drug fluid (drawn up in a non-aseptic environment by the anesthesiologist) and dispensed by an electronic pump. Precedex is being used with patients in the intensive care unit (ICU), during neurosurgery and for children during MRI.
Precedex is delivered via intravenous infusion over a selected amount of time through a controlled infusion with the use of an electronic or battery operated pump or with a “smart pump”. A pre-filled and non-electric pump that is therapy specific could allow more widespread use of novel sedation agents (such as Precedex), because of the ability to administer the therapy in a safer and more efficient manner without the need for multiple steps and sophisticated software routines.
The novel dispenser of the present invention provides numerous advantages over prior art devices including the following:
Creation of a standard operating procedure for the administration of propofol by anesthesiologists and non-anesthesiologists alike.
Elimination of the need for filling syringes, thereby reducing the potential for medication errors due to filling (i.e. using the wrong concentration of propofol) or use of a drug that is similar in appearance to propofol.
Elimination of the need for an electronic pump, thereby reducing the potential for medication error due to incorrect settings.
Reducing costs to healthcare providers and practitioners by eliminating expensive electronic capital equipment that requires continuous maintenance, calibration and cleaning.
Elimination of the requirement for electricity in austere or chaotic environments (e.g. during military engagements, natural disasters).
Presentation of the sedation agent at the point of care in an aseptic manner as a single self-contained unit-dose pre-filled delivery system should also minimize the probability of hospital acquired infection.
As previously mentioned, a significant market for the pre-filled unit-dose small volume dispenser of the present invention is the endoscopy center market. In this regard, one form of the dispenser of the present invention is specially designed for relatively short procedures (i.e. 20-30 minutes), such as colonoscopies and endoscopies. More particularly, the dispenser of the invention, which is non-electric and disposable following use, can provide an extremely cost effective means of increasing efficiency in the endoscopy center. The dispenser uniquely provides an alternative to expensive electronic pumps that are often complicated and time consuming to operate. In addition, low cost disposable devices for use in outpatient clinics are consistent with a broader theme in healthcare that is aimed at lowering costs while improving quality of care and patient outcomes. Because physicians in the endoscopy center are searching for a cost effective means to increase patient throughput within the center, the dispenser of the present invention provides a natural fit for a standardized sedation process for colonoscopies and endoscopies, without compromising the quality and safety of the procedure.
In another form of the present invention, the dispenser comprises a mid-volume propofol delivery systems technology (65 ml) that is specially designed for use in the surgicenter for procedures that require sedation times of 1-2 hours. In this application a novel dispenser can serve as a safe and effective means for patients that are to be fitted with orthopedic and cardiac implants. Similarly, this novel mid-volume dispenser can function well with minimum discomfort for general surgeries such as hernia repairs and the like. Because physicians in the surgicenter market are often quite time conscious, the dispenser of the present invention comprises a natural fit for a standardized sedation process that could potentially increase patient throughput within the market without compromising the quality and safety of the procedure. Additionally, patients prefer propofol as an anesthetic agent because there is no “hangover” effect, which stems from its ease of titration and rapid elimination half-life. By way of comparison, traditional anesthesia with gas has a very slow elimination half-life and patients require long recovery times that are typically complicated by nausea and vomiting. Conversely, propofol has inherent antiemetic properties, which chemically combats feelings of nausea.
In yet another form of the present invention, the dispenser comprises a large volume propofol dispenser (250 ml) that is specially designed for use in military applications, including total W anesthesia (TIVA) by the Forward Surgical Team at the battlefield, as well as for sedation of the patient during transport from one echelon of care to the next. This form of the invention can provide a safe and effective means to sedate a patient during an operation and throughout transport without relying on bulky medical equipment or expensive equipment that is transported with the patient and never returned to the original care facility.
As will be fully appreciated from the discussion that follows, the devices of the present invention-are also particularly useful in ambulatory situations. The ability to quickly and efficaciously treat wounded soldiers, especially in unpredictable or remote care settings, can significantly improve chances for patient survival and recovery. Accurate intravenous (IV) drug and fluid delivery technologies for controlling pain, preventing infection, and providing a means for IV access for rapid infusions during patient transport are needed to treat almost all serious injuries.
It is imperative that battlefield medics begin administering life saving medications as soon as possible after a casualty occurs. The continuous maintenance of these treatments is vital until higher echelon medical facilities can be reached. A compact, portable and ready to use infusion device that could be easily brought into the battlefield would allow medics to begin drug and resuscitation agent infusions immediately. Additionally, it would free them to attend to other seriously wounded patients who may require more hands-on care in the trauma environment following triage. In most serious trauma situations on the battlefield, IV drug delivery is required to treat fluid resuscitation, as well as both pain and infection. Drug infusion devices currently available can impede administration of IV infusions in remote care settings.
Expensive electronic infusion pumps are not a practical field solution because of their weight and cumbersome size. Moreover, today's procedures for starting IV infusions on the battlefield are often dangerous because the attending medic must complete several time consuming steps. The labor intensive nature of current gravity solution bag modalities can prevent medics from attending to other patients also suffering from life threatening injuries. In some cases, patients themselves have been forced to hold flexible infusion bags elevated, in order to receive the medication by gravity drip.